1. Field of the Invention
The present invention relates generally to electronic filters, and more particularly to a switchable bandwidth lowpass filter as may be used in conjunction with controlling a fiber optic transceiver.
2. Description of the Prior Art
It is desirable to have a fiberoptic transmitter or receiver whose bandwidth can be varied by a control input, to match the frequency characteristics of more than one fiberoptic transmitter (Tx) or receiver (Rx) in communication with the first Rx or Tx. In prior art devices, the receivers or transmitters are designed to have predetermined frequency characteristic that is not dynamically adjustable. This results in devices that are specific to particular applications and are not universal in nature. In addition, these devices do not allow for a migration path to higher bandwidth systems without replacing the receiver and/or transmitter.
Filters, such as simple RC filters, for example, are sometimes used in applications where it is desirable to change the characteristics of a Tx or Rx. For example, a particular filter may work best with a fast time constant under certain circumstances, under different circumstances, a relatively slow time constant may be required. Either the filter's resistance or the capacitance may be varied, for example, to change the characteristics of these filters.
There is a need to provide a simple, yet efficient, circuit for providing bandwidth swichability to fiberoptic transceivers.